Fluid actuated gage for internal measurements



Nov. 29, 1966 E. A. HOLLIS 3,287,811

FLUID ACTUATED GAGE FOR INTERNAL MEASUREMENTS Filed June 5, 1964 j Z? Z3 INVENTOR 5 /3 Z/G Evev a++4 HoHis mR PRESSURE SUPPLY REGULHTOR 14 BY QMQDQELD ATTOR NEYS United States Patent Qfifice 3,287,811 Patented Nov. 29, 1%66 3,287,811 FLUID ACTUATED GAGE FOR INTERNAL MEASUREMENTS Everett A. Hollis, Granby, Conn, assignor to Pratt & Whitney, Inc., a corporation of Delaware Filed June 3, 1964, Ser. No. 372,205 2 Claims. (Cl. 33-147) This invention relates to gaging devices and more particularly relates to a fluid-actuated gaging head for gaging the inside diameter of circular bores.

Pneumatic gaging systems are generally well known in the art. Such gages may be generally classified into two types, the back pressure type and the flow type. The back pressure type gage utilizes pressure changes in an air supply line occasioned by flow through a variable size orifice to indicate a dimension or deviation from a standard dimension. The flow type gage measures the flow of air through a variable size orifice for the same purposes. A gaging head or plug embodying the present invention for purposes of disclosure will be exemplified in a back pressure type system.

The present invention provides a gaging head or plug which is simple in construction and assembly and which utilizes only a small amount of component parts. Moreover, a gaging head constructed in accordance with this invention may be easily disassembled for cleaning purposes and reassembled in a short period of time. Further, a gaging head constructed in accordance with this invention readily lends itself to use in either a back pressure type gaging system or a flow type gaging system.

Accordingly, an object of this invention is to provide a new and improved gaging head for use in a pneumatic gaging system for gaging the inside diameter of circular bores.

Another object of this invention is to provide a pneumatic gaging head which comprises only a few number of parts and which is economical to manufacture.

A further object of this invention is to provide a new and improved pneumatic gaging head for gaging the inside diameter of circular rbores which may be easily disassembled for cleaning purposes and quickly reassembled.

The features of the invention which are believed to be novel are pointed out with particularity and distinctly claimed in the concluding portion of this specification. However, the invention both as to its construction and operation, together with further objects and advanages thereof, may best be appreciated by reference to the following detailed description taken in conjunction with the drawings wherein:

FIG. 1 is an end view seen from the gaging end of a pneumatic gaging head constructed in accordance with the invention;

FIG. 2 is a side elevation of the gaging head of FIG. 1;

FIG. 3 is a sectional view of the gaging head of FIG. I seen along line 33 of FIG. 1;

FIG. 4 is a view of a contact pin utilized in the gaging heads shown in FIGS. 1-3; and

FIG. 5 schematically exemplifies a back pressure pneumatic gaging system with which a gaging head embodying the invention may 'be utilized.

In accordance with the invention a gage head is pro vided for workpieces having cylindrical bores therein and comprises a substantially cylindrical gaging head having movably supported therein diametrically opposed gaging pins which are arranged to be actuated relative to the gaging head by engagement with the inner diameter of the workpiece. The contact pins, dependent on the position thereof, vary the flow oat an expansible fluid, such as air, through an axial bore in the gaging head in accordance with the size of the bore being gaged. The change in fluid flow or change in pressure is accurately indicated on an indicating instrument and the size of the here or a deviation in the size of the bore from a standard size is thereby determined in a manner more fully explained in conjunction with FIG. 5.

In the drawings a gaging head embodying the invention is generally indicated by the reference numeral 10 and comprises a cylindrical body or plug portion 11 having a bore 12 axially therethrough. The gaging head further comprises an adaptor or spindle portion 13 adapted to receive and be connected to a fluid supply conduit 14, FIG. 5. As illustrated, the connector portion has internal threads 15 to receive conduit 14.

The body portion 11 has contact pin-receiving bores 16a and 16b diametrically therethrough. The axes of the bores 16 a and 16b are coincident and intersect the axis of axial bore 12. Bores 16a and 16b receive therein gaging contact pins 17. The pins 17 are cylindrical and are formed with substantially hemispherical contact surfaces 18. The contact surfaces, if not completely hemispherical, are formed in the shape of a section of a spherical surface, or domed. The opposite ends of the pins 17 are flat and in planes square with the axis of the pins.

As more clearly shown in FIG. 4 each contact pin intermediate its ends is provided with a slot 19 therethrough to a depth substantially equal to the radius of the pin.

Longitudinally defined in body 11 in substantially diametrically opposed positions are retaining slots or keyways 21 which are counterbored as at 22. Keyways 21 receive therein keys 20 in the form of a pin or rod having an eyelet type head 24 received in the counterbored portion 22. The rodlike key 20 extends into the slot 19 in each of contact pins 17 and retains each pin 17 in its respective bore. The rodlike keys are so dimensioned with respect to the slots 19 that they allow predetermined movement of the pins in their respective bores while retaining the conatct pins in the gaging head.

The diameter d of bore 12 is greater on the air inlet side of the gaging head than the diameter d on the air exhaust side of the gaging head, the inlet and exhaust sides being spoken of with reference to the location of the contact pins. The reason for this difference in diameter of the feed and exhaust bore is hereinafter explained.

It may be seen that the disclosed gaging head comprises only a minimal number of parts, namely, the cylindrical body member or plug 11, two contact pins 17, and two retaining keys 20. In assembly the pins 17, which have a slip fit with their respective bores 16a and 1611, are positioned in the bores and then the keys 20 are inserted in keyways 21 and extend into slots 19 in the pins. If the gaging head should require cleaning the eyelet type heads 24 of the keys 20 may be easily grasped and removed from the keyways. Then the pins may be slipped out of their bores and the gaging head cleaned. The gaging head may be then rapidly reassembled as previously explained.

In operation, the plug 11 is inserted within the bore whose diameter is to be gaged. The walls of the bore will be contacted by the spherical heads of the contact pins and fluid, preferably air under presure, will be directed down bore 12. The air moving through the orifice or throttle defined by the parallel back ends of the contact pins will exert a pressure on the ends of the pins forcing them toward the walls of the bore to be gaged. The size of the orifice defined between the pins in bore 12 will then determine the back pressure of the fluid in the inlet side of bore 12. This back pressure is then a measure of the diameter of the bore being gaged, or the deviation of the bore from a standard size.

A typical back pressure pneumatic gaging system is illustrated in FIG. 5 and comprises a supply of air under pressure 25, such as a pump or compressor, a pressure regulator 26 and associated pressure gage 27, a restriction exemplified by valve 28 and a pressure measuring gage 29 which may be calibrated to read the diameter of the bore being gaged or the deviation of the diameter of the bore from a predetermined size. Gage 29 will indicate the pressure in conduit 14 and hence the pressure on the inlet side of bore 12. Gage 29 is preferably calibrated to read directly the diameter of the bore being gaged or the deviation in diameter thereof.

In the disclosed gaging head the contact pins have a relatively loose fit in the bores 16:: and 16b. For this reason the diameter d is made greater than the diameter 01 to provide reinforcement against cocking or tilting of the pins in their bores when fluid under pressure is applied to bore 12. Inasmuch as the pins 17 have a slip fit within their respective bores, some air may escape through the pin bores. In order to equalize the leakage through the bores 16a and 16b longitudinally extending grooves 36 are provided on either side of the plug portion 11 which are interrupted by the bores 16a and 16b, thus if the plug should be inserted in a bore to be gaged eccentric to the axis thereof and one contact pin forced entirely into its bore, the longitudinal grooves along that side of the plug will allow escape of the leakage air and prevent inaccur-acies due to such insertion of the plug in the bore.

In practice, the diameter of the cylindrical body member or plug 11 is made slightly less than the minimum bore to be checked. The diameter of pins 17 is chosen in accordance with the requirements of the particular gaging system, primarily in accordance with the pressure of the fluid applied to bore 12. The length of the two contact pins 17 are such that the sum of their lengths is slightly less than the diameter of the body member.

It may thus be seen that the objects set forth as well as those made apparent are efficiently attained. While a preferred embodiment of the invention has been set forth for purposes of disclosure, modification of the disclosed embodiment of the invention as well as other embodiments is to be gaged, said plug member having an axial bore longitudinally therethrough and a bore diametrically therethrough defining two gaging pin bores, cylindrical gaging pins in each of said gaging pin bores, said pins having slots defined therein intermediate the ends thereof, said plug member having two keyways defined longitudinally therein from one end thereof communicating with the gaging pin bores, and pin retaining keys in said key- Ways extending into the slots in said pins to retain said pins in said plug and allow limited movement of said pins in their bores, the axial bore comprising portions having a greater diameter on one side of the diametrical bore than on the other side thereof, and the pins of a length such that they always extend into both the smaller and larger diameter portions of the axial bore when retained in their bores.

2.. A gaging device comprising a cylindrical plug member adapted to be inserted in a bore whose diameter is to be gaged, said plug member having an axial bore longitudinally therethrough and I2. bore diametrically therethrough defining gaging pin bores, cylinder gaging pins in each of the gaging pin bores and movable longitudinally therein, said axial bore comprising portions of a diameter al on one side of the diametri-cal bore and a diameter d on the other side of the bore, wherein d is greater than d and the bore portion of diameter a is adapted to be connected to the inlet side of the plug and the bore portion of diameter d is adapted to be connected to the exhaust side of the plug, a first means for retaining said pins in their diarnetrioal bores while allowing limited movement therein, and said pins of a length such that when retained in the plug by the first means they extend into both of the axial bore portions having diameters d and d References Cited by the Examiner UNITED STATES PATENTS 2,565,844 8/1951 Eisele 33178 2,581,473 1/1952 Eisele 33-l78 2,622,331 12/ 1952 Haines.

2,680,912 6/ 4 Wylie.

2,737,727 3/ 1956 Aller 33 LOUIS R. PRINCE, Primary Examiner.

DAVID SCHONBERG, Examiner.

F. H. THOMSON, Assistant Examiner. 

1. A GAGING DEVICE COMPRISING A CYLINDRICAL PLUG MEMBER ADAPTED TO BE INSERTED IN A BORE WHOSE DIAMETER IS TO BE GAGED, SAID PLUG MEMBER HAVING AN AXIAL BORE LONGITUDINALLY THERETHROUGH AND A BORE DIAMETRICALLY THERETHROUGH DEFINING TWO GAGING PIN BORES, CYLINDRICAL GAGING PINS IN EACH OF SAID GAGING PIN BORES, SAID PINS HAVING SLOTS DEFINED THEREIN INTERMEDIATE THE ENDS THEREOF, SAID PLUG MEMBER HAVING TWO KEYWAYS DEFINED LONGITUDINALLY THEREIN FROM ONE END THEREOF COMMUNICATING WITH THE GAGING PIN BORES, AND PIN RETAINING KEYS IN SAID KEYWAYS EXTENDING INTO THE SLOTS IN SAID PINS TO RETAIN SAID PINS IN SAID PLUG AND ALLOW LIMITED MOVEMENT OF SAID PINS IN THEIR BORES, THE AXIAL BORE COMPRISING PORTIONS HAVING A GREATER DIAMETER ON ONE SIDE OF THE DIAMETRICAL 